This invention relates generally to the conversion of methanol so as to produce gasoline and, more particularly, to the control of carbon monoxide emissions resulting from the regeneration of the spent methanol conversion catalyst.
The conversion of methanol to gasoline is an important area of technology which has the potential of becoming even more important as the supply of crude oil is diminished and/or increased in price. Particularly advantageous catalysts which are utilized for the conversion of methanol to gasoline are a special class of crystalline aluminosilicate zeolites of which ZSM-5 is the most preferred member. There are many patents which describe the conversion of methanol to gasoline over said special zeolites, including U.S. Pat. Nos. 3,931,349; 3,969,426; 3,899,544; 3,894,107; 3,907,914; and 3,894,102.
As is known in the art, the catalytic conversion of methanol to produce gasoline over zeolites such as ZSM-5 results in the deposition of carbonaceous material, generally referred to as coke, on the catalyt thereby resulting in decline of activity of said catalyst which must be compensated for by regeneration of the same by burning off said coke at elevated temperatures in the regenerator. The art is well aware that among the products resulting from the combustion of coke are carbon monoxide and carbon dioxide. Recent environmental regulations by the state and Federal governments have seriously limited the amount of carbon monoxide which can be discharged to the atmosphere and, as such, there is need for a process wherein carbon monoxide can be combusted in the regenerator so as to minimize the atmospheric pollution.
Although there is much art involving the combustion of carbon monoxide in a regenerator, this art is really concerned with the catalytic cracking of gas oil to produce gasoline and not the catalytic conversion of methanol to gasoline. Art dealing with the control of carbon monoxide from a catalytic cracking process can be represented by U.S. Pat. Nos. 4,072,600; 4,088,568; and 4,093,535.
In addition, copending application Ser. No. 152,458 filed May 22, 1980 deals with the use of platinum catalysts to control the CO emission in a methanol conversion process to produce gasoline.